They aren't Apple Computers anymore because everything is a computer. The iPhone is a mini computer. So's the AppleTV. But they don't want to call it a computer. They want you to stop thinking of it like that, stop focusing on the underneath and start focusing on the interface. It's the start (well, continuation) of something new, so it's a good way to separate it from the old way we used to think of "computers".
Except for the fact that they didn't release any actual computers (they will soon, I'm sure) I can't wait.